Thursday, November 16, 2017

Tree of the Week: Winged Sumac (Rhus copallina)

Our tree of the week is the winged sumac (Rhus copallina). This small tree is doing more than its fair-share in the fall foliage game, and it's almost impossible to miss if you're walking between Mickle Hall and the Student Union Building. The young tree has an array of red, orange and green leaves, the red hues being amplified by the remaining green leaves.

Rhus copallina has been represented in the arboretum since 1995. In the fall of 1994, Ed Leuck collected two plants in town, along south Line Avenue, and he planted them in the ground the following autumn. One plant grew marvelously for many years. You can see pictures of it here. But this past spring, during a rain storm, the medium-sized tree unexpectedly fell over. Luckily, a clone of it remains. The small tree near the sidewalk popped up from the roots of the original tree approximately five years ago. Today it's providing marvelous color to the arboretum landscape and in years to come it will be providing much needed shade during the summer months.
This small, very colorful tree, is the arboretum's only winged sumac (Rhus copallina). It initially grew from the roots of an older tree which has since died; this specimen is approximately 5 years old. In years to come, it will provide much needed shade for this east-west walkway. The Mickle Hall auditorium is the brick structure pictured in the background, and you can see the campus greenhouse on top of the roof.
Winged sumacs have large leaves that turn beautiful colors in the fall. So much color!
There are still a few green leaves on the tree, and quite a few leaves are in the process of turning. The tree might be more stunning in this stage, while the red and green complementary colors are side-by-side, rather than when the tree has lost all of its greenness.
Winged sumac leaves are pinnately compound. The leaf on the left is missing a leaflet: back in the spring it surely had 11. The leaf on the right has 13 leaflets.
Underneath, the leaves are light green, considerably less stunning.
The winged sumac gets its name from the midrib, which is lined with protruding flat 'wings'.
For comparison, we have (partial) leaves from two different Rhus species. Rhus glabra is the mostly red leaf at the top of the photograph, and Rhus copallina is the multi-colored leaf at the bottom. 
Zooming in on the two different leaves, we see that the leaf stalk of R. glabra is thin and round. The R. copallina leaf stalk is flat and noticeably wider. This photo also shows that the leaflets differ: the leaf margins of R. glabra are toothed, while the leaf margins of R. copallina are smooth. 
The branch bark is a silvery gray.

You can see old pictures of the arboretum's recently deceased winged sumac here.

For more information about this species consult the following:
United States Department of Agriculture
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter)
University of Florida (IFAS Extension)

Tuesday, November 14, 2017

Autumn Update

This is an early-autumn view of the arboretum. The photo was taken about two months ago, on September 20, 2017. The grass is green; the trees, for the most part, have green leaves; and the crown of the sweet gum is starting to turn red.
From September to November, the colors have changed. This photo is from last weekend, taken on November 11, 2017. The grass is going dormant, losing its greenness. Leaves of Magnolia grandiflora and Quercus texana remain obstinately green, while the little mockernut hickory has lost all of its leaves. The crown of the sweet gum tree is really red now! And we have an extra splotch of color: the crown of the Carolina ash, which is peeking out from behind the magnolia, has turned yellow-orange.
Fall foliage of Sassafras albidum
Pictured from left to right: Acer rubrum, Sassafras albidum, Liquidambar styraciflua, and Fraxinus caroliniana.

Sunday, November 12, 2017

Tree of the Week: Carolina Ash (Fraxinus caroliniana)

Our tree of the week is best appreciated from afar. Stand back and take in the stunning color of its crown. Carolina ash (Fraxinus caroliniana) has been living on the grounds of the arboretum since 1995. In the spring of '94, Ed Leuck collected a specimen from Walter Jacobs Nature Park. The young tree was nurtured in a pot for over a year before being planted in November 1995. From the very moment of its arrival, it has been in fierce competition with a swamp white oak (Quercus michauxii), which was planted the same November. The photos below show that despite the rivalry for solar resources, there was plenty of sunlight for both. 
The orange-yellow rounded top of the Carolina ash stands out in the arboretum's landscape. The tree-top to the left belongs to a swamp white oak (Quercus michauxii), which was planted at the same time as the Carolina ash.
Following the pretty orange leaves down to the ground, we can notice how straight this ash tree is. It has grown in tough competition that has resulted in heavy shade on the ground.
This Carolina ash is doing marvelously at the bottom of a hill along the arboretum drainage. This area gets a lot of water, but doesn't experience flooding.
This tree has a very straight trunk with the leaves way up top, out of reach.
There are still some green leaves mixed in with the fall foliage.
Zooming in on those few remaining green leaves, we see that they are pinnately compound with 5 to 7 leaflets.
On the ground we can find only leaf parts. Here we have a rachis with two remaining yellow-orange leaflets. These leaflets have smooth edges which isn't common for the species.
Flipping it over, we see the leaflets are greenish-white.
The leaf-litter offers a variety of colors: red-orange, dark-red, and yellow.
The light colored bark is composed of rough ridges.

For more information about this species consult the following:
United States Department of Agriculture 
Virginia Tech Dendrology
Louisiana Plant Identification and Interactive Virtual Tours (LSU AgCenter) 

Saturday, November 4, 2017

Tree of the Week: Smooth Sumac (Rhus glabra)

We first noted the fall foliage of the smooth sumac (Rhus glabra) back in September, in an 'Autumn Update'. The transformation is now complete: all the leaves have turned red, of varying shades. 

The smooth sumac entered the arboretum collection in October 1996 when Ed Leuck collected several specimens from the wilds of Caddo Parish. These were nurtured in pots until 1998 when they were planted in the ground on one of the arboretum's many clay slopes. By the year 2000, the sumacs in this initial planting had sent out their roots and established a second patch. The smooth sumacs you'll see today in the arboretum (and in the picture below) are from the second patch; the original plantings were later removed.

Smooth sumacs tend to develop as bushes rather than trees. In this grouping, which has been growing since 2000, there is one small tree and approximately 10 younger, smaller shoots, forming a thicket.
The trunk of the small tree can be identified in this photo. It appears to be leaning to the left.
Another view shows that the tree is leaning down-slope and seems to be partially propped-up by a rock.
In the fall, smooth sumac leaves are stunning shades of red.
The compound leaves are very long. This one measures more than 18 inches.
The underside is a pale pink.
The long-pointed red leaflets have toothed margins. In this photo we can see that the petioles are red, too.
This leaflet measures to 4 inches.
This is the trunk of the small tree, approximately 17 years of age. The bark is dark gray and lightly textured.

You can see more pictures of the arboretum's smooth sumacs here.

For more information about this species consult the following:
Texas Native Plants Database (Texas A&M University)
United States Department of Agriculture
NC State University 

Friday, October 27, 2017

Tree of the Week: Loblolly Pine (Pinus taeda)

There are five on-site-native loblolly pines (Pinus taeda) in the arboretum collection. These trees have been growing unaided on the clay slopes of the campus since we-don't-know-when, and they have survived the construction of our campus buildings. They grow here naturally, spontaneously, and they grow to be very tall. The photos below are of an individual loblolly near Hamilton Hall.

This is a very shady spot in the arboretum. The large loblolly trunk is pictured in the middle, with an on-site-native water oak (Quercus nigra) pictured to the right, closer to the brick retaining wall.
Looking down the slope, the tall, cylindrical trunk of the loblolly is pictured in the center. The green leaves are a long way up, out of view, but there is a good amount of pine straw on the ground.

The green leaves are only seen from a distance, way up high. Pinus taeda is pictured in the middle, with Quercus nigra pictured on the right.
These leaves (needles) are 7 inches long. The singular needles appear in bundles of three.
For comparison, spruce pine (Pinus glabra) leaves are pictured above the loblolly leaves. The spruce pine needles are much shorter, measuring approximately 2.5 inches long.
Prickly cones are dropping out of the loblolly.
This cone measures to about 5 inches long and 3 inches wide.
The spruce pine cone (pictured on the left) is much smaller than the loblolly cone.
Walking through the arboretum, you will most likely only see the trunks of the loblolly pines. Mature loblolly bark is reddish-brown and heavily fissured.
The bark is formed into large thick plates.

You can see more pictures of the arboretum's loblolly pines here.

Check out the following links for more information about this species:
United States Department of Agriculture
USDA Forest Service
Oklahoma Forestry Services
Louisiana Plant Identification and Interactive Virtual Tours 

Friday, October 20, 2017

Tree of the Week: Red Bay (Persea borbonia)

The red bay (Persea borbonia) is a founding species for the arboretum; the arboretum has been home to multiple specimens since it began. Ed Leuck collected one individual from Bienville Parish and two from Kisatchie National Forest. Another tree was purchased from Woodlanders nursery (Aiken, S.C.). Well-suited to the local enviroment and having a prolific nature, volunteers abound every year from the four original trees. Most of these young trees are removed; some are allowed to stay; and yet others are collected and relocated.

The pictures below are of a single volunteer that was collected and cultivated for several years in the greenhouse. In the spring of 2003, it was finally transplanted back into the arboretum where it has become an established tree. Today you can find it in a large iris bed on the floodplain. Despite a noticeable crook in its trunk, the tree is doing well, so well that the irises are now struggling for light.

This red bay grows in the arboretum's floodplain. When we get a heavy rain, a lot of water passes through this area and it is slow to dry. Carpinus caroliniana is pictured in the background. A large on-site-native Pinus taeda is pictured behind and to the left of the C. caroliniana.
The swamp titi trees team up with the red bay to shade the wooden foot bridge that runs from the Fitness Center to the Student Union Building, providing much needed relief from the sun during the summer months.
This red bay leans westward, perhaps vying for more sun. Its competition includes Carpinus carolinana, Pinus taeda and Quercus alba. At a younger age, it was in competition with Cyrilla racemiflora.
The red bay is evergreen, which is bad news for the irises living under it.
Fruits of the red bay are ripening this time of year.
The dark blue drupes are numerous.
The top leaf surface is smooth and shiny. The leaves are narrow and have slightly wavy edges. A spicy aroma is released if you crush or crumple these leaves, making them a culinary substitute for the bay leaves you buy in the grocery store.
The drupe itself is black, concealed by the blue covering, which slips off if you squeeze it. The leaf is pale-green underneath and fuzzy to the touch.
The blue slip covering is green on the inside.
Reddish-gray furrowed bark of a tree that is approximately 20-years-old

You can find more pictures of the arboretum's red bays here.

For more information about this species consult the following:
University of Florida IFAS Extension 
United States Department of Agriculture
US Forest Service 
Louisiana Plant Identification and Interactive Virtual Tours